This invention relates to gas turbine engines, and more particularly, to a pulse detonation system for a gas turbine engine.
Variable cycle turbofan ramjet engines may be used to provide aircraft flight speeds between low subsonic Mach numbers to high supersonic Mach numbers of about Mach 6. Known engines, as described in U.S. Pat. No. 5,694,768, include a core engine system and a dual mode augmentor. The dual mode augmentor provides additional beat to exhaust airflow exiting the core engine system to increase engine thrust. The core engine system provides power to drive a fan assembly and typically includes in serial, axial flow relationship, a compressor, a combustor, a high pressure turbine, and a low pressure turbine. The dual mode augmentor is positioned downstream from the core engine and receives air from the core engine and a bypass duct surrounding the core engine. However, augmentors are limited to a level of thrust increase by stoichiometry, and as a result, for an engine to operate efficiently over a wide range of operating flight speeds, several different combustion systems may be required.
To facilitate optimizing thrust production, at least some known engines include pulse detonation systems which replace a conventional augmentor on a turbofan or turbojet engine, and which utilize a deflagration process and a detonation process. The deflagration process is implemented using a plurality of mechanical valving. However, the performance of such systems is generally limited because of inherent deficiencies that may exist because the deflagration process consumes energy without the benefit of detonation, which occurs only on the remainder of any unconsumed fuel. Additionally, any benefits gained from using such pulse detonation systems, may be offset by an overall weight of the system.